settings: Fix the type annotation for color-hash
settings: Fix the type annotation for color-hash

The (element-type) annotation cannot be used with properties that return
container types like GHashTable; we need to use the (type) annotation.

https://bugzilla.gnome.org/show_bug.cgi?id=750489

alexlarsson/gtk,grubersjoe/adwaita,grubersjoe/adwaita,Adamovskiy/gtk,Adamovskiy/gtk,jadahl/gtk,davidgumberg/gtk,Adamovskiy/gtk,Adamovskiy/gtk,jigpu/gtk,jigpu/gtk,alexlarsson/gtk,chergert/gtk,Adamovskiy/gtk,jadahl/gtk,chergert/gtk,alexlarsson/gtk,chergert/gtk,jadahl/gtk,davidgumberg/gtk,jadahl/gtk,grubersjoe/adwaita,jadahl/gtk,chergert/gtk,chergert/gtk,Adamovskiy/gtk,jadahl/gtk,davidgumberg/gtk,jigpu/gtk,alexlarsson/gtk,Adamovskiy/gtk,jadahl/gtk,jigpu/gtk,Adamovskiy/gtk,grubersjoe/adwaita,grubersjoe/adwaita,alexlarsson/gtk,chergert/gtk,davidgumberg/gtk,alexlarsson/gtk,alexlarsson/gtk,grubersjoe/adwaita,jigpu/gtk,davidgumberg/gtk,davidgumberg/gtk,chergert/gtk,jigpu/gtk,davidgumberg/gtk,jigpu/gtk,grubersjoe/adwaita,davidgumberg/gtk,grubersjoe/adwaita,chergert/gtk,jigpu/gtk,alexlarsson/gtk,jadahl/gtk